1. Field of the Invention
The present invention relates to a method of fabricating a wire grid polarizer, and more particularly, to a method of fabricating a wire grid polarizer having a fine structure over a large area.
2. Description of the Related Art
In general, wire grid polarizers have a wire grid structure in which stripe-shaped metal wires having a certain pitch are arranged on a transparent substrate. If the pitch of the metal wires is similar to or greater than the wavelength of an electromagnetic wave, diffraction occurs. However, if the pitch of the metal wires is significantly smaller than the wavelength of the electromagnetic wave, split of polarization occurs. That is, if the pitch of the metal wires, that is, a distance between adjacent metal wires, is sufficiently small, light polarized parallel to the metal wires, that is, S-polarized light, is reflected by the metal wires, and light polarized perpendicular to the metal wires, that is, P-polarized light, is transmitted through the metal wires. The width, thickness, and pitch of the metal wires affect the polarization characteristics, such as the transmittance and reflectance, of the wire grid polarizer.
In order for a wire grid polarizer to be used for visible light having wavelengths of 400 to 700 nm, the wire grid polarizer is generally required to have a pitch of less than λ/5, that is, a feature size of less than 100 nm. However, it is very difficult to fabricate a wire grid having a feature size of less than 100 nm using conventional semiconductor photolithography, and particularly difficult to form a pattern over a large area. A conventional method of fabricating a wire grid polarizer comprises forming a master pattern using E-beam lithography, fabricating a mold, which is a reverse image of the master pattern, using electroplating, sequentially stacking a metal layer and a polymer layer on a transparent substrate to form a pattern on the polymer layer using the mold, and depositing a metal grid on the pattern using oblique deposition. However, the conventional method is too complicated for mass production of the wire grid polarizer, and equipment, such as vacuum deposition equipment, required for the conventional method is expensive. Thus, the conventional method is not commercially viable. Furthermore, since a wire grid polarizer fabricated using the conventional method has a size of several inches, it is difficult to apply the wire grid polarizer to a large liquid crystal display (LCD) panel having a size of several tens of inches.